1. Field of the Invention
The present invention relates to gelling agents. The present invention also relates to gel compositions which containing such a gelling agent. The present invention further relates to novel N-acylamino acid monoamide monoalkyl esters and novel pyrrolidone derivatives.
2. Discussion of the Background
Heretofore, as a gelling agent for water-insoluble oily base materials, generally known are polyamide resin, 12-hydroxystearic acid, fatty acid dextrin, fatty acid inulin, fatty acid glycerin and dibenzylidene-D-sorbitol, which is the condensate of aromatic aldehyde and polyalcohol. However, these gelling agents have a low solubility in oily base materials, and therefore, the dissolving state of the gel composition using them is bad, and the gel composition becomes non-uniform and has a problem in that the gelled oily base material bleeds out of the gel surface owing to the change with time, therefore causing a so-called “sweating phenomenon”.
As a gelling agent that has solved these problems, a cosmetic containing an N-acyl-L-glutamic acid dibutylamide has been reported (see, JP-A 51-19139 and JP-A 2002-31697). It is known that it may gel various oily base materials, but its solubility in ordinary oily base materials is low, and when the gelling agent is dissolved, it requires a high temperature of 150° C. or so, and therefore this is not always suitable for the case of incorporating a substance having poor thermal stability and a volatile component.
Thus, a gelling agent having a melting temperature of about 100° C., capable of solidifying a wide variety of oily base materials including silicone, causing no “sweating” while retaining a practical level of gel strength, showing a good feeling during application to skin, concretely showing good gel spreadability, and capable of well fitting to skin is eagerly desired.